Glossary term: Uranus

Description: Uranus is the seventh farthest planet from the Sun. It was discovered in 1781 by William Herschel. Thus, it was the first planet to be found since antiquity. Its diameter is four times that of Earth, but it does not have a firm surface. Like Neptune, Uranus is an ice giant. Uranus has a solid rock core surrounded by a layer of high-pressure water, methane, and ammonia. In the early outer Solar System these chemicals were frozen. The young Uranus accreted these "ices", hence the name "ice giant". Uranus's outer atmosphere is a thick, puffy layer of hydrogen and helium. Its rotational axis is tilted by more than 90 degrees relative to the orbital plane. Uranus has a ring system and more than 25 moons.

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The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".

Related Media

Uranus showing a uniformly greenish-blue coloured appearance

Uranus in natural colours

Caption: This is an image of the planet Uranus taken by the spacecraft Voyager 2 in 1986. Its appearance is close to what the naked eye would see. The greenish-blue colour indicates an atmosphere containing methane.
Credit: NASA/JPL-Caltech credit link
License: PD Public Domain icons
Uranus appears as a light blue disk with and a pale polar region. Thin white rings surround the planet

Uranus with rings

Caption: The NASA/ESA Hubble Space Telescope’s ACS/HRC camera observed Uranus in August 2005. The surface depicts white clouds and a bright polar region. The rings around Uranus are narrow and contain rocky material from tiny dust particles up to metre-sized boulders.
Credit: NASA, ESA, and M. Showalter (SETI Institute) credit link
License: PD Public Domain icons